THE JOINTS 158
It runs between the arch of the atlas and the anterior margin of the foramen magnum. The meinbrana tectoria continues the posterior common ligament to the cranial surface of the basi-occipital bone. And the posterior occipito-atlantoid ligament runs from the posterior arch of the atlas to the posterior border of the foramen magnum; it is strengthened by accessory bands. The posterior oceipito-axoid ligament (fig. 26, P.O-A.L.) is a strong band on each side on the deep aspect of the meinbrana tectoria. It passes lateral to the odontoid process and conceals the spinal aspect of the transverse ligament (T.L.). The latter runs between the inferior atlantic articular processes, and passes behind the odontoid process. The cruciate ligament has no inferior crus in the Chimpanzee, but the superior crus (S.C.C.) is shorter and broader than in Man. The middle odontoid and check (C.L.) ligaments are more horizontal than in Man.
Costo-vertebral Ligaments (fig. 26).—The head of each rib is connected to the anterior common ligament of the spine by a fan-shaped ligament (A.C.L.K Superior, middle and posterior costo-transverse ligaments are present, but the first and third are weaker than in Man.
Ligaments of the Pelvis $g. -26, P).—In the Chimpanzee the lumbar vertebrae are included more closely between the ilia than in Man. The lumbo-inguinal ligaments (L.LL.) consist of an upper horizontal and a lower fan-shaped band connecting the transverse processes of the third and fourth lumbar vertebrae to the inner lip of the iliac crest and the anterior surface of the dorsum ilii. The surfaces of the sacrum are connected